org.apache.tomcat.dbcp.pool.impl.GenericKeyedObjectPool Maven / Gradle / Ivy
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* (the "License"); you may not use this file except in compliance with
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*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.tomcat.dbcp.pool.impl;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.TreeMap;
import java.util.TimerTask;
import java.util.Map.Entry;
import org.apache.tomcat.dbcp.pool.BaseKeyedObjectPool;
import org.apache.tomcat.dbcp.pool.KeyedObjectPool;
import org.apache.tomcat.dbcp.pool.KeyedPoolableObjectFactory;
import org.apache.tomcat.dbcp.pool.PoolUtils;
import org.apache.tomcat.dbcp.pool.PoolableObjectFactory;
/**
* A configurable KeyedObjectPool implementation.
*
* When coupled with the appropriate {@link KeyedPoolableObjectFactory},
* GenericKeyedObjectPool provides robust pooling functionality for
* keyed objects. A GenericKeyedObjectPool can be viewed as a map
* of pools, keyed on the (unique) key values provided to the
* {@link #preparePool preparePool}, {@link #addObject addObject} or
* {@link #borrowObject borrowObject} methods. Each time a new key value is
* provided to one of these methods, a new pool is created under the given key
* to be managed by the containing GenericKeyedObjectPool.
*
* A GenericKeyedObjectPool provides a number of configurable
* parameters:
*
* -
* {@link #setMaxActive maxActive} controls the maximum number of objects
* (per key) that can allocated by the pool (checked out to client threads,
* or idle in the pool) at one time. When non-positive, there is no limit
* to the number of objects per key. When {@link #setMaxActive maxActive} is
* reached, the keyed pool is said to be exhausted. The default setting for
* this parameter is 8.
*
* -
* {@link #setMaxTotal maxTotal} sets a global limit on the number of objects
* that can be in circulation (active or idle) within the combined set of
* pools. When non-positive, there is no limit to the total number of
* objects in circulation. When {@link #setMaxTotal maxTotal} is exceeded,
* all keyed pools are exhausted. When
maxTotal is set to a
* positive value and {@link #borrowObject borrowObject} is invoked
* when at the limit with no idle instances available, an attempt is made to
* create room by clearing the oldest 15% of the elements from the keyed
* pools. The default setting for this parameter is -1 (no limit).
*
* -
* {@link #setMaxIdle maxIdle} controls the maximum number of objects that can
* sit idle in the pool (per key) at any time. When negative, there
* is no limit to the number of objects that may be idle per key. The
* default setting for this parameter is 8.
*
* -
* {@link #setWhenExhaustedAction whenExhaustedAction} specifies the
* behavior of the {@link #borrowObject borrowObject} method when a keyed
* pool is exhausted:
*
* -
* When {@link #setWhenExhaustedAction whenExhaustedAction} is
* {@link #WHEN_EXHAUSTED_FAIL}, {@link #borrowObject borrowObject} will throw
* a {@link NoSuchElementException}
*
* -
* When {@link #setWhenExhaustedAction whenExhaustedAction} is
* {@link #WHEN_EXHAUSTED_GROW}, {@link #borrowObject borrowObject} will create a new
* object and return it (essentially making {@link #setMaxActive maxActive}
* meaningless.)
*
* -
* When {@link #setWhenExhaustedAction whenExhaustedAction}
* is {@link #WHEN_EXHAUSTED_BLOCK}, {@link #borrowObject borrowObject} will block
* (invoke {@link Object#wait() wait} until a new or idle object is available.
* If a positive {@link #setMaxWait maxWait}
* value is supplied, the {@link #borrowObject borrowObject} will block for at
* most that many milliseconds, after which a {@link NoSuchElementException}
* will be thrown. If {@link #setMaxWait maxWait} is non-positive,
* the {@link #borrowObject borrowObject} method will block indefinitely.
*
*
* The default whenExhaustedAction setting is
* {@link #WHEN_EXHAUSTED_BLOCK}.
*
* -
* When {@link #setTestOnBorrow testOnBorrow} is set, the pool will
* attempt to validate each object before it is returned from the
* {@link #borrowObject borrowObject} method. (Using the provided factory's
* {@link KeyedPoolableObjectFactory#validateObject validateObject} method.)
* Objects that fail to validate will be dropped from the pool, and a
* different object will be borrowed. The default setting for this parameter
* is
false.
*
* -
* When {@link #setTestOnReturn testOnReturn} is set, the pool will
* attempt to validate each object before it is returned to the pool in the
* {@link #returnObject returnObject} method. (Using the provided factory's
* {@link KeyedPoolableObjectFactory#validateObject validateObject}
* method.) Objects that fail to validate will be dropped from the pool.
* The default setting for this parameter is
false.
*
*
*
* Optionally, one may configure the pool to examine and possibly evict objects
* as they sit idle in the pool and to ensure that a minimum number of idle
* objects is maintained for each key. This is performed by an
* "idle object eviction" thread, which runs asynchronously. Caution should be
* used when configuring this optional feature. Eviction runs contend with client
* threads for access to objects in the pool, so if they run too frequently
* performance issues may result. The idle object eviction thread may be
* configured using the following attributes:
*
* -
* {@link #setTimeBetweenEvictionRunsMillis timeBetweenEvictionRunsMillis}
* indicates how long the eviction thread should sleep before "runs" of examining
* idle objects. When non-positive, no eviction thread will be launched. The
* default setting for this parameter is -1 (i.e., by default, idle object
* eviction is disabled).
*
* -
* {@link #setMinEvictableIdleTimeMillis minEvictableIdleTimeMillis}
* specifies the minimum amount of time that an object may sit idle in the
* pool before it is eligible for eviction due to idle time. When
* non-positive, no object will be dropped from the pool due to idle time
* alone. This setting has no effect unless
*
timeBetweenEvictionRunsMillis > 0. The default setting
* for this parameter is 30 minutes.
*
* -
* {@link #setTestWhileIdle testWhileIdle} indicates whether or not idle
* objects should be validated using the factory's
* {@link KeyedPoolableObjectFactory#validateObject validateObject} method
* during idle object eviction runs. Objects that fail to validate will be
* dropped from the pool. This setting has no effect unless
*
timeBetweenEvictionRunsMillis > 0. The default setting
* for this parameter is false.
*
* -
* {@link #setMinIdle minIdle} sets a target value for the minimum number of
* idle objects (per key) that should always be available. If this parameter
* is set to a positive number and
*
timeBetweenEvictionRunsMillis > 0, each time the idle object
* eviction thread runs, it will try to create enough idle instances so that
* there will be minIdle idle instances available under each
* key. This parameter is also used by {@link #preparePool preparePool}
* if true is provided as that method's
* populateImmediately parameter. The default setting for this
* parameter is 0.
*
*
*
* The pools can be configured to behave as LIFO queues with respect to idle
* objects - always returning the most recently used object from the pool,
* or as FIFO queues, where borrowObject always returns the oldest object
* in the idle object pool.
*
* -
* {@link #setLifo Lifo}
* determines whether or not the pools return idle objects in
* last-in-first-out order. The default setting for this parameter is
*
true.
*
*
*
* GenericKeyedObjectPool is not usable without a {@link KeyedPoolableObjectFactory}. A
* non-null factory must be provided either as a constructor argument
* or via a call to {@link #setFactory setFactory} before the pool is used.
*
*
* Implementation note: To prevent possible deadlocks, care has been taken to
* ensure that no call to a factory method will occur within a synchronization
* block. See POOL-125 and DBCP-44 for more information.
*
* @see GenericObjectPool
* @author Rodney Waldhoff
* @author Dirk Verbeeck
* @author Sandy McArthur
* @version $Revision: 990683 $ $Date: 2010-08-29 21:40:36 -0400 (Sun, 29 Aug 2010) $
* @since Pool 1.0
*/
public class GenericKeyedObjectPool extends BaseKeyedObjectPool implements KeyedObjectPool {
//--- public constants -------------------------------------------
/**
* A "when exhausted action" type indicating that when the pool is
* exhausted (i.e., the maximum number of active objects has
* been reached), the {@link #borrowObject}
* method should fail, throwing a {@link NoSuchElementException}.
* @see #WHEN_EXHAUSTED_BLOCK
* @see #WHEN_EXHAUSTED_GROW
* @see #setWhenExhaustedAction
*/
public static final byte WHEN_EXHAUSTED_FAIL = 0;
/**
* A "when exhausted action" type indicating that when the pool
* is exhausted (i.e., the maximum number
* of active objects has been reached), the {@link #borrowObject}
* method should block until a new object is available, or the
* {@link #getMaxWait maximum wait time} has been reached.
* @see #WHEN_EXHAUSTED_FAIL
* @see #WHEN_EXHAUSTED_GROW
* @see #setMaxWait
* @see #getMaxWait
* @see #setWhenExhaustedAction
*/
public static final byte WHEN_EXHAUSTED_BLOCK = 1;
/**
* A "when exhausted action" type indicating that when the pool is
* exhausted (i.e., the maximum number
* of active objects has been reached), the {@link #borrowObject}
* method should simply create a new object anyway.
* @see #WHEN_EXHAUSTED_FAIL
* @see #WHEN_EXHAUSTED_GROW
* @see #setWhenExhaustedAction
*/
public static final byte WHEN_EXHAUSTED_GROW = 2;
/**
* The default cap on the number of idle instances (per key) in the pool.
* @see #getMaxIdle
* @see #setMaxIdle
*/
public static final int DEFAULT_MAX_IDLE = 8;
/**
* The default cap on the total number of active instances (per key)
* from the pool.
* @see #getMaxActive
* @see #setMaxActive
*/
public static final int DEFAULT_MAX_ACTIVE = 8;
/**
* The default cap on the the overall maximum number of objects that can
* exist at one time.
* @see #getMaxTotal
* @see #setMaxTotal
*/
public static final int DEFAULT_MAX_TOTAL = -1;
/**
* The default "when exhausted action" for the pool.
* @see #WHEN_EXHAUSTED_BLOCK
* @see #WHEN_EXHAUSTED_FAIL
* @see #WHEN_EXHAUSTED_GROW
* @see #setWhenExhaustedAction
*/
public static final byte DEFAULT_WHEN_EXHAUSTED_ACTION = WHEN_EXHAUSTED_BLOCK;
/**
* The default maximum amount of time (in milliseconds) the
* {@link #borrowObject} method should block before throwing
* an exception when the pool is exhausted and the
* {@link #getWhenExhaustedAction "when exhausted" action} is
* {@link #WHEN_EXHAUSTED_BLOCK}.
* @see #getMaxWait
* @see #setMaxWait
*/
public static final long DEFAULT_MAX_WAIT = -1L;
/**
* The default "test on borrow" value.
* @see #getTestOnBorrow
* @see #setTestOnBorrow
*/
public static final boolean DEFAULT_TEST_ON_BORROW = false;
/**
* The default "test on return" value.
* @see #getTestOnReturn
* @see #setTestOnReturn
*/
public static final boolean DEFAULT_TEST_ON_RETURN = false;
/**
* The default "test while idle" value.
* @see #getTestWhileIdle
* @see #setTestWhileIdle
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public static final boolean DEFAULT_TEST_WHILE_IDLE = false;
/**
* The default "time between eviction runs" value.
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public static final long DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS = -1L;
/**
* The default number of objects to examine per run in the
* idle object evictor.
* @see #getNumTestsPerEvictionRun
* @see #setNumTestsPerEvictionRun
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public static final int DEFAULT_NUM_TESTS_PER_EVICTION_RUN = 3;
/**
* The default value for {@link #getMinEvictableIdleTimeMillis}.
* @see #getMinEvictableIdleTimeMillis
* @see #setMinEvictableIdleTimeMillis
*/
public static final long DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS = 1000L * 60L * 30L;
/**
* The default minimum level of idle objects in the pool.
* @since Pool 1.3
* @see #setMinIdle
* @see #getMinIdle
*/
public static final int DEFAULT_MIN_IDLE = 0;
/**
* The default LIFO status. True means that borrowObject returns the
* most recently used ("last in") idle object in a pool (if there are
* idle instances available). False means that pools behave as FIFO
* queues - objects are taken from idle object pools in the order that
* they are returned.
* @see #setLifo
*/
public static final boolean DEFAULT_LIFO = true;
//--- constructors -----------------------------------------------
/**
* Create a new GenericKeyedObjectPool with no factory.
*
* @see #GenericKeyedObjectPool(KeyedPoolableObjectFactory)
* @see #setFactory(KeyedPoolableObjectFactory)
*/
public GenericKeyedObjectPool() {
this(null, DEFAULT_MAX_ACTIVE, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE,
DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,
DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy
* objects if not null
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory) {
this(factory, DEFAULT_MAX_ACTIVE, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE,
DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,
DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param config a non-null {@link GenericKeyedObjectPool.Config} describing the configuration
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, GenericKeyedObjectPool.Config config) {
this(factory, config.maxActive, config.whenExhaustedAction, config.maxWait, config.maxIdle, config.maxTotal,
config.minIdle, config.testOnBorrow, config.testOnReturn, config.timeBetweenEvictionRunsMillis,
config.numTestsPerEvictionRun, config.minEvictableIdleTimeMillis, config.testWhileIdle, config.lifo);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive) {
this(factory,maxActive, DEFAULT_WHEN_EXHAUSTED_ACTION, DEFAULT_MAX_WAIT, DEFAULT_MAX_IDLE,
DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,
DEFAULT_NUM_TESTS_PER_EVICTION_RUN, DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
* whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
long maxWait) {
this(factory, maxActive, whenExhaustedAction, maxWait, DEFAULT_MAX_IDLE, DEFAULT_TEST_ON_BORROW,
DEFAULT_TEST_ON_RETURN, DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
* whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
* method (see {@link #setTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
* method (see {@link #setTestOnReturn})
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
long maxWait, boolean testOnBorrow, boolean testOnReturn) {
this(factory, maxActive, whenExhaustedAction, maxWait, DEFAULT_MAX_IDLE,testOnBorrow,testOnReturn,
DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed from me at one time
* (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
* whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
long maxWait, int maxIdle) {
this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, DEFAULT_TEST_ON_BORROW, DEFAULT_TEST_ON_RETURN,
DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed from me at one time
* (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
* whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
* method (see {@link #setTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
* method (see {@link #setTestOnReturn})
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn) {
this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, testOnBorrow, testOnReturn,
DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS, DEFAULT_NUM_TESTS_PER_EVICTION_RUN,
DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS, DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed from me at one time
* (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted
* (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
* whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
* method (see {@link #setTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
* method (see {@link #setTestOnReturn})
* @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
* objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
* @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
* thread (if any) (see {@link #setNumTestsPerEvictionRun})
* @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
* it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
* @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
* (see {@link #setTestWhileIdle})
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis,
int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle) {
this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, GenericKeyedObjectPool.DEFAULT_MAX_TOTAL,
testOnBorrow, testOnReturn, timeBetweenEvictionRunsMillis, numTestsPerEvictionRun,
minEvictableIdleTimeMillis, testWhileIdle);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed from me at one time
* (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
* whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
* @param maxTotal the maximum number of objects that can exists at one time (see {@link #setMaxTotal})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
* method (see {@link #setTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
* method (see {@link #setTestOnReturn})
* @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
* objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
* @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
* thread (if any) (see {@link #setNumTestsPerEvictionRun})
* @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool
* before it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
* @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
* (see {@link #setTestWhileIdle})
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
long maxWait, int maxIdle, int maxTotal, boolean testOnBorrow, boolean testOnReturn,
long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis,
boolean testWhileIdle) {
this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, maxTotal,
GenericKeyedObjectPool.DEFAULT_MIN_IDLE, testOnBorrow, testOnReturn, timeBetweenEvictionRunsMillis,
numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed at one time (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
* whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
* @param maxTotal the maximum number of objects that can exists at one time (see {@link #setMaxTotal})
* @param minIdle the minimum number of idle objects to have in the pool at any one time (see {@link #setMinIdle})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
* method (see {@link #setTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
* method (see {@link #setTestOnReturn})
* @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
* objects
* for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
* @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
* thread (if any) (see {@link #setNumTestsPerEvictionRun})
* @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
* it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
* @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
* (see {@link #setTestWhileIdle})
* @since Pool 1.3
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
long maxWait, int maxIdle, int maxTotal, int minIdle, boolean testOnBorrow, boolean testOnReturn,
long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis,
boolean testWhileIdle) {
this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, maxTotal, minIdle, testOnBorrow, testOnReturn,
timeBetweenEvictionRunsMillis, numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle,
DEFAULT_LIFO);
}
/**
* Create a new GenericKeyedObjectPool using the specified values.
* @param factory the KeyedPoolableObjectFactory to use to create, validate, and destroy objects
* if not null
* @param maxActive the maximum number of objects that can be borrowed at one time
* (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted and
* whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
* @param maxTotal the maximum number of objects that can exists at one time (see {@link #setMaxTotal})
* @param minIdle the minimum number of idle objects to have in the pool at any one time (see {@link #setMinIdle})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject}
* method (see {@link #setTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject}
* method (see {@link #setTestOnReturn})
* @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle
* objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
* @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction
* thread (if any) (see {@link #setNumTestsPerEvictionRun})
* @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before
* it is eligible for eviction (see {@link #setMinEvictableIdleTimeMillis})
* @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any
* (see {@link #setTestWhileIdle})
* @param lifo whether or not the pools behave as LIFO (last in first out) queues (see {@link #setLifo})
* @since Pool 1.4
*/
public GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, byte whenExhaustedAction,
long maxWait, int maxIdle, int maxTotal, int minIdle, boolean testOnBorrow, boolean testOnReturn,
long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis,
boolean testWhileIdle, boolean lifo) {
_factory = factory;
_maxActive = maxActive;
_lifo = lifo;
switch (whenExhaustedAction) {
case WHEN_EXHAUSTED_BLOCK:
case WHEN_EXHAUSTED_FAIL:
case WHEN_EXHAUSTED_GROW:
_whenExhaustedAction = whenExhaustedAction;
break;
default:
throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
}
_maxWait = maxWait;
_maxIdle = maxIdle;
_maxTotal = maxTotal;
_minIdle = minIdle;
_testOnBorrow = testOnBorrow;
_testOnReturn = testOnReturn;
_timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
_numTestsPerEvictionRun = numTestsPerEvictionRun;
_minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
_testWhileIdle = testWhileIdle;
_poolMap = new HashMap();
_poolList = new CursorableLinkedList();
startEvictor(_timeBetweenEvictionRunsMillis);
}
//--- public methods ---------------------------------------------
//--- configuration methods --------------------------------------
/**
* Returns the cap on the number of object instances allocated by the pool
* (checked out or idle), per key.
* A negative value indicates no limit.
*
* @return the cap on the number of active instances per key.
* @see #setMaxActive
*/
public synchronized int getMaxActive() {
return _maxActive;
}
/**
* Sets the cap on the number of object instances managed by the pool per key.
* @param maxActive The cap on the number of object instances per key.
* Use a negative value for no limit.
*
* @see #getMaxActive
*/
public synchronized void setMaxActive(int maxActive) {
_maxActive = maxActive;
allocate();
}
/**
* Returns the overall maximum number of objects (across pools) that can
* exist at one time. A negative value indicates no limit.
* @return the maximum number of instances in circulation at one time.
* @see #setMaxTotal
*/
public synchronized int getMaxTotal() {
return _maxTotal;
}
/**
* Sets the cap on the total number of instances from all pools combined.
* When maxTotal is set to a
* positive value and {@link #borrowObject borrowObject} is invoked
* when at the limit with no idle instances available, an attempt is made to
* create room by clearing the oldest 15% of the elements from the keyed
* pools.
*
* @param maxTotal The cap on the total number of instances across pools.
* Use a negative value for no limit.
* @see #getMaxTotal
*/
public synchronized void setMaxTotal(int maxTotal) {
_maxTotal = maxTotal;
allocate();
}
/**
* Returns the action to take when the {@link #borrowObject} method
* is invoked when the pool is exhausted (the maximum number
* of "active" objects has been reached).
*
* @return one of {@link #WHEN_EXHAUSTED_BLOCK},
* {@link #WHEN_EXHAUSTED_FAIL} or {@link #WHEN_EXHAUSTED_GROW}
* @see #setWhenExhaustedAction
*/
public synchronized byte getWhenExhaustedAction() {
return _whenExhaustedAction;
}
/**
* Sets the action to take when the {@link #borrowObject} method
* is invoked when the pool is exhausted (the maximum number
* of "active" objects has been reached).
*
* @param whenExhaustedAction the action code, which must be one of
* {@link #WHEN_EXHAUSTED_BLOCK}, {@link #WHEN_EXHAUSTED_FAIL},
* or {@link #WHEN_EXHAUSTED_GROW}
* @see #getWhenExhaustedAction
*/
public synchronized void setWhenExhaustedAction(byte whenExhaustedAction) {
switch(whenExhaustedAction) {
case WHEN_EXHAUSTED_BLOCK:
case WHEN_EXHAUSTED_FAIL:
case WHEN_EXHAUSTED_GROW:
_whenExhaustedAction = whenExhaustedAction;
allocate();
break;
default:
throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
}
}
/**
* Returns the maximum amount of time (in milliseconds) the
* {@link #borrowObject} method should block before throwing
* an exception when the pool is exhausted and the
* {@link #setWhenExhaustedAction "when exhausted" action} is
* {@link #WHEN_EXHAUSTED_BLOCK}.
*
* When less than or equal to 0, the {@link #borrowObject} method
* may block indefinitely.
*
* @return the maximum number of milliseconds borrowObject will block.
* @see #setMaxWait
* @see #setWhenExhaustedAction
* @see #WHEN_EXHAUSTED_BLOCK
*/
public synchronized long getMaxWait() {
return _maxWait;
}
/**
* Sets the maximum amount of time (in milliseconds) the
* {@link #borrowObject} method should block before throwing
* an exception when the pool is exhausted and the
* {@link #setWhenExhaustedAction "when exhausted" action} is
* {@link #WHEN_EXHAUSTED_BLOCK}.
*
* When less than or equal to 0, the {@link #borrowObject} method
* may block indefinitely.
*
* @param maxWait the maximum number of milliseconds borrowObject will block or negative for indefinitely.
* @see #getMaxWait
* @see #setWhenExhaustedAction
* @see #WHEN_EXHAUSTED_BLOCK
*/
public synchronized void setMaxWait(long maxWait) {
_maxWait = maxWait;
}
/**
* Returns the cap on the number of "idle" instances per key.
* @return the maximum number of "idle" instances that can be held
* in a given keyed pool.
* @see #setMaxIdle
*/
public synchronized int getMaxIdle() {
return _maxIdle;
}
/**
* Sets the cap on the number of "idle" instances in the pool.
* If maxIdle is set too low on heavily loaded systems it is possible you
* will see objects being destroyed and almost immediately new objects
* being created. This is a result of the active threads momentarily
* returning objects faster than they are requesting them them, causing the
* number of idle objects to rise above maxIdle. The best value for maxIdle
* for heavily loaded system will vary but the default is a good starting
* point.
* @param maxIdle the maximum number of "idle" instances that can be held
* in a given keyed pool. Use a negative value for no limit.
* @see #getMaxIdle
* @see #DEFAULT_MAX_IDLE
*/
public synchronized void setMaxIdle(int maxIdle) {
_maxIdle = maxIdle;
allocate();
}
/**
* Sets the minimum number of idle objects to maintain in each of the keyed
* pools. This setting has no effect unless
* timeBetweenEvictionRunsMillis > 0 and attempts to ensure
* that each pool has the required minimum number of instances are only
* made during idle object eviction runs.
* @param poolSize - The minimum size of the each keyed pool
* @since Pool 1.3
* @see #getMinIdle
* @see #setTimeBetweenEvictionRunsMillis
*/
public void setMinIdle(int poolSize) {
_minIdle = poolSize;
}
/**
* Returns the minimum number of idle objects to maintain in each of the keyed
* pools. This setting has no effect unless
* timeBetweenEvictionRunsMillis > 0 and attempts to ensure
* that each pool has the required minimum number of instances are only
* made during idle object eviction runs.
* @return minimum size of the each keyed pool
* @since Pool 1.3
* @see #setTimeBetweenEvictionRunsMillis
*/
public int getMinIdle() {
return _minIdle;
}
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* before being returned by the {@link #borrowObject}
* method. If the object fails to validate,
* it will be dropped from the pool, and we will attempt
* to borrow another.
*
* @return true if objects are validated before being borrowed.
* @see #setTestOnBorrow
*/
public boolean getTestOnBorrow() {
return _testOnBorrow;
}
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* before being returned by the {@link #borrowObject}
* method. If the object fails to validate,
* it will be dropped from the pool, and we will attempt
* to borrow another.
*
* @param testOnBorrow whether object should be validated before being returned by borrowObject.
* @see #getTestOnBorrow
*/
public void setTestOnBorrow(boolean testOnBorrow) {
_testOnBorrow = testOnBorrow;
}
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* before being returned to the pool within the
* {@link #returnObject}.
*
* @return true when objects will be validated before being returned.
* @see #setTestOnReturn
*/
public boolean getTestOnReturn() {
return _testOnReturn;
}
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* before being returned to the pool within the
* {@link #returnObject}.
*
* @param testOnReturn true so objects will be validated before being returned.
* @see #getTestOnReturn
*/
public void setTestOnReturn(boolean testOnReturn) {
_testOnReturn = testOnReturn;
}
/**
* Returns the number of milliseconds to sleep between runs of the
* idle object evictor thread.
* When non-positive, no idle object evictor thread will be
* run.
*
* @return milliseconds to sleep between evictor runs.
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized long getTimeBetweenEvictionRunsMillis() {
return _timeBetweenEvictionRunsMillis;
}
/**
* Sets the number of milliseconds to sleep between runs of the
* idle object evictor thread.
* When non-positive, no idle object evictor thread will be
* run.
*
* @param timeBetweenEvictionRunsMillis milliseconds to sleep between evictor runs.
* @see #getTimeBetweenEvictionRunsMillis
*/
public synchronized void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis) {
_timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
startEvictor(_timeBetweenEvictionRunsMillis);
}
/**
* Returns the max number of objects to examine during each run of the
* idle object evictor thread (if any).
*
* @return number of objects to examine each eviction run.
* @see #setNumTestsPerEvictionRun
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized int getNumTestsPerEvictionRun() {
return _numTestsPerEvictionRun;
}
/**
* Sets the max number of objects to examine during each run of the
* idle object evictor thread (if any).
*
* When a negative value is supplied,
* ceil({@link #getNumIdle()})/abs({@link #getNumTestsPerEvictionRun})
* tests will be run. I.e., when the value is -n, roughly one nth of the
* idle objects will be tested per run. When the value is positive, the number of tests
* actually performed in each run will be the minimum of this value and the number of instances
* idle in the pools.
*
* @param numTestsPerEvictionRun number of objects to examine each eviction run.
* @see #setNumTestsPerEvictionRun
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized void setNumTestsPerEvictionRun(int numTestsPerEvictionRun) {
_numTestsPerEvictionRun = numTestsPerEvictionRun;
}
/**
* Returns the minimum amount of time an object may sit idle in the pool
* before it is eligible for eviction by the idle object evictor
* (if any).
*
* @return minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
* @see #setMinEvictableIdleTimeMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized long getMinEvictableIdleTimeMillis() {
return _minEvictableIdleTimeMillis;
}
/**
* Sets the minimum amount of time an object may sit idle in the pool
* before it is eligible for eviction by the idle object evictor
* (if any).
* When non-positive, no objects will be evicted from the pool
* due to idle time alone.
*
* @param minEvictableIdleTimeMillis minimum amount of time an object may sit idle in the pool before
* it is eligible for eviction.
* @see #getMinEvictableIdleTimeMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis) {
_minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
}
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* by the idle object evictor (if any). If an object
* fails to validate, it will be dropped from the pool.
*
* @return true when objects are validated when borrowed.
* @see #setTestWhileIdle
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized boolean getTestWhileIdle() {
return _testWhileIdle;
}
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* by the idle object evictor (if any). If an object
* fails to validate, it will be dropped from the pool.
*
* @param testWhileIdle true so objects are validated when borrowed.
* @see #getTestWhileIdle
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized void setTestWhileIdle(boolean testWhileIdle) {
_testWhileIdle = testWhileIdle;
}
/**
* Sets the configuration.
* @param conf the new configuration to use.
* @see GenericKeyedObjectPool.Config
*/
public synchronized void setConfig(GenericKeyedObjectPool.Config conf) {
setMaxIdle(conf.maxIdle);
setMaxActive(conf.maxActive);
setMaxTotal(conf.maxTotal);
setMinIdle(conf.minIdle);
setMaxWait(conf.maxWait);
setWhenExhaustedAction(conf.whenExhaustedAction);
setTestOnBorrow(conf.testOnBorrow);
setTestOnReturn(conf.testOnReturn);
setTestWhileIdle(conf.testWhileIdle);
setNumTestsPerEvictionRun(conf.numTestsPerEvictionRun);
setMinEvictableIdleTimeMillis(conf.minEvictableIdleTimeMillis);
setTimeBetweenEvictionRunsMillis(conf.timeBetweenEvictionRunsMillis);
}
/**
* Whether or not the idle object pools act as LIFO queues. True means
* that borrowObject returns the most recently used ("last in") idle object
* in a pool (if there are idle instances available). False means that
* the pools behave as FIFO queues - objects are taken from idle object
* pools in the order that they are returned.
*
* @return true if the pools are configured to act as LIFO queues
* @since 1.4
*/
public synchronized boolean getLifo() {
return _lifo;
}
/**
* Sets the LIFO property of the pools. True means that borrowObject returns
* the most recently used ("last in") idle object in a pool (if there are
* idle instances available). False means that the pools behave as FIFO
* queues - objects are taken from idle object pools in the order that
* they are returned.
*
* @param lifo the new value for the lifo property
* @since 1.4
*/
public synchronized void setLifo(boolean lifo) {
this._lifo = lifo;
}
//-- ObjectPool methods ------------------------------------------
/**
*
Borrows an object from the keyed pool associated with the given key.
*
* If there is an idle instance available in the pool associated with the given key, then
* either the most-recently returned (if {@link #getLifo() lifo} == true) or "oldest" (lifo == false)
* instance sitting idle in the pool will be activated and returned. If activation fails, or
* {@link #getTestOnBorrow() testOnBorrow} is set to true and validation fails, the instance is destroyed and the
* next available instance is examined. This continues until either a valid instance is returned or there
* are no more idle instances available.
*
* If there are no idle instances available in the pool associated with the given key, behavior
* depends on the {@link #getMaxActive() maxActive}, {@link #getMaxTotal() maxTotal}, and (if applicable)
* {@link #getWhenExhaustedAction() whenExhaustedAction} and {@link #getMaxWait() maxWait} properties. If the
* number of instances checked out from the pool under the given key is less than maxActive and
* the total number of instances in circulation (under all keys) is less than maxTotal, a new instance
* is created, activated and (if applicable) validated and returned to the caller.
*
* If the associated keyed pool is exhausted (no available idle instances and no capacity to create new ones),
* this method will either block ({@link #WHEN_EXHAUSTED_BLOCK}), throw a NoSuchElementException
* ({@link #WHEN_EXHAUSTED_FAIL}), or grow ({@link #WHEN_EXHAUSTED_GROW} - ignoring maxActive, maxTotal properties).
* The length of time that this method will block when whenExhaustedAction == WHEN_EXHAUSTED_BLOCK
* is determined by the {@link #getMaxWait() maxWait} property.
*
* When the pool is exhausted, multiple calling threads may be simultaneously blocked waiting for instances
* to become available. As of pool 1.5, a "fairness" algorithm has been implemented to ensure that threads receive
* available instances in request arrival order.
*
* @param key pool key
* @return object instance from the keyed pool
* @throws NoSuchElementException if a keyed object instance cannot be returned.
*/
public Object borrowObject(Object key) throws Exception {
long starttime = System.currentTimeMillis();
Latch latch = new Latch(key);
byte whenExhaustedAction;
long maxWait;
synchronized (this) {
// Get local copy of current config. Can't sync when used later as
// it can result in a deadlock. Has the added advantage that config
// is consistent for entire method execution
whenExhaustedAction = _whenExhaustedAction;
maxWait = _maxWait;
// Add this request to the queue
_allocationQueue.add(latch);
// Work the allocation queue, allocating idle instances and
// instance creation permits in request arrival order
allocate();
}
for(;;) {
synchronized (this) {
assertOpen();
}
// If no object was allocated
if (null == latch.getPair()) {
// Check to see if we were allowed to create one
if (latch.mayCreate()) {
// allow new object to be created
} else {
// the pool is exhausted
switch(whenExhaustedAction) {
case WHEN_EXHAUSTED_GROW:
// allow new object to be created
synchronized (this) {
// Make sure another thread didn't allocate us an object
// or permit a new object to be created
if (latch.getPair() == null && !latch.mayCreate()) {
_allocationQueue.remove(latch);
latch.getPool().incrementInternalProcessingCount();
}
}
break;
case WHEN_EXHAUSTED_FAIL:
synchronized (this) {
// Make sure allocate hasn't already assigned an object
// in a different thread or permitted a new object to be created
if (latch.getPair() != null || latch.mayCreate()) {
break;
}
_allocationQueue.remove(latch);
}
throw new NoSuchElementException("Pool exhausted");
case WHEN_EXHAUSTED_BLOCK:
try {
synchronized (latch) {
// Before we wait, make sure another thread didn't allocate us an object
// or permit a new object to be created
if (latch.getPair() == null && !latch.mayCreate()) {
if (maxWait <= 0) {
latch.wait();
} else {
// this code may be executed again after a notify then continue cycle
// so, need to calculate the amount of time to wait
final long elapsed = (System.currentTimeMillis() - starttime);
final long waitTime = maxWait - elapsed;
if (waitTime > 0)
{
latch.wait(waitTime);
}
}
} else {
break;
}
}
} catch(InterruptedException e) {
synchronized (this) {
// Make sure allocate hasn't already assigned an object
// in a different thread or permitted a new object to be created
if (latch.getPair() == null && !latch.mayCreate()) {
_allocationQueue.remove(latch);
} else {
break;
}
}
Thread.currentThread().interrupt();
throw e;
}
if (maxWait > 0 && ((System.currentTimeMillis() - starttime) >= maxWait)) {
synchronized (this) {
// Make sure allocate hasn't already assigned an object
// in a different thread or permitted a new object to be created
if (latch.getPair() == null && !latch.mayCreate()) {
_allocationQueue.remove(latch);
} else {
break;
}
}
throw new NoSuchElementException("Timeout waiting for idle object");
} else {
continue; // keep looping
}
default:
throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction +
" not recognized.");
}
}
}
boolean newlyCreated = false;
if (null == latch.getPair()) {
try {
Object obj = _factory.makeObject(key);
latch.setPair(new ObjectTimestampPair(obj));
newlyCreated = true;
} finally {
if (!newlyCreated) {
// object cannot be created
synchronized (this) {
latch.getPool().decrementInternalProcessingCount();
// No need to reset latch - about to throw exception
allocate();
}
}
}
}
// activate & validate the object
try {
_factory.activateObject(key, latch.getPair().value);
if (_testOnBorrow && !_factory.validateObject(key, latch.getPair().value)) {
throw new Exception("ValidateObject failed");
}
synchronized (this) {
latch.getPool().decrementInternalProcessingCount();
latch.getPool().incrementActiveCount();
}
return latch.getPair().value;
} catch (Throwable e) {
PoolUtils.checkRethrow(e);
// object cannot be activated or is invalid
try {
_factory.destroyObject(key, latch.getPair().value);
} catch (Throwable e2) {
PoolUtils.checkRethrow(e2);
// cannot destroy broken object
}
synchronized (this) {
latch.getPool().decrementInternalProcessingCount();
if (!newlyCreated) {
latch.reset();
_allocationQueue.add(0, latch);
}
allocate();
}
if (newlyCreated) {
throw new NoSuchElementException(
"Could not create a validated object, cause: " +
e.getMessage());
}
else {
continue; // keep looping
}
}
}
}
/**
* Allocate available instances to latches in the allocation queue. Then
* set _mayCreate to true for as many additional latches remaining in queue
* as _maxActive allows for each key.
*/
private void allocate() {
boolean clearOldest = false;
synchronized (this) {
if (isClosed()) return;
Iterator allocationQueueIter = _allocationQueue.iterator();
while (allocationQueueIter.hasNext()) {
// First use any objects in the pool to clear the queue
Latch latch = (Latch) allocationQueueIter.next();
ObjectQueue pool = (ObjectQueue)(_poolMap.get(latch.getkey()));
if (null == pool) {
pool = new ObjectQueue();
_poolMap.put(latch.getkey(), pool);
_poolList.add(latch.getkey());
}
latch.setPool(pool);
if (!pool.queue.isEmpty()) {
allocationQueueIter.remove();
latch.setPair(
(ObjectTimestampPair) pool.queue.removeFirst());
pool.incrementInternalProcessingCount();
_totalIdle--;
synchronized (latch) {
latch.notify();
}
// Next item in queue
continue;
}
// If there is a totalMaxActive and we are at the limit then
// we have to make room
if ((_maxTotal > 0) &&
(_totalActive + _totalIdle + _totalInternalProcessing >= _maxTotal)) {
clearOldest = true;
break;
}
// Second utilise any spare capacity to create new objects
if ((_maxActive < 0 || pool.activeCount + pool.internalProcessingCount < _maxActive) &&
(_maxTotal < 0 || _totalActive + _totalIdle + _totalInternalProcessing < _maxTotal)) {
// allow new object to be created
allocationQueueIter.remove();
latch.setMayCreate(true);
pool.incrementInternalProcessingCount();
synchronized (latch) {
latch.notify();
}
// Next item in queue
continue;
}
// If there is no per-key limit and we reach this point we
// must have allocated all the objects we possibly can and there
// is no point looking at the rest of the allocation queue
if (_maxActive < 0) {
break;
}
}
}
if (clearOldest) {
/* Clear oldest calls factory methods so it must be called from
* outside the sync block.
* It also needs to be outside the sync block as it calls
* allocate(). If called inside the sync block, the call to
* allocate() would be able to enter the sync block (since the
* thread already has the lock) which may have unexpected,
* unpleasant results.
*/
clearOldest();
}
}
/**
* Clears any objects sitting idle in the pool by removing them from the
* idle instance pool and then invoking the configured PoolableObjectFactory's
* {@link KeyedPoolableObjectFactory#destroyObject(Object, Object)} method on
* each idle instance.
*
* Implementation notes:
*
- This method does not destroy or effect in any way instances that are
* checked out when it is invoked.
* - Invoking this method does not prevent objects being
* returned to the idle instance pool, even during its execution. It locks
* the pool only during instance removal. Additional instances may be returned
* while removed items are being destroyed.
* - Exceptions encountered destroying idle instances are swallowed.
*/
public void clear() {
Map toDestroy = new HashMap();
synchronized (this) {
for (Iterator it = _poolMap.keySet().iterator(); it.hasNext();) {
Object key = it.next();
ObjectQueue pool = (ObjectQueue)_poolMap.get(key);
// Copy objects to new list so pool.queue can be cleared inside
// the sync
List objects = new ArrayList();
objects.addAll(pool.queue);
toDestroy.put(key, objects);
it.remove();
_poolList.remove(key);
_totalIdle = _totalIdle - pool.queue.size();
_totalInternalProcessing =
_totalInternalProcessing + pool.queue.size();
pool.queue.clear();
}
}
destroy(toDestroy, _factory);
}
/**
* Clears oldest 15% of objects in pool. The method sorts the
* objects into a TreeMap and then iterates the first 15% for removal.
*
* @since Pool 1.3
*/
public void clearOldest() {
// Map of objects to destroy my key
final Map toDestroy = new HashMap();
// build sorted map of idle objects
final Map map = new TreeMap();
synchronized (this) {
for (Iterator keyiter = _poolMap.keySet().iterator(); keyiter.hasNext();) {
final Object key = keyiter.next();
final CursorableLinkedList list = ((ObjectQueue)_poolMap.get(key)).queue;
for (Iterator it = list.iterator(); it.hasNext();) {
// each item into the map uses the objectimestamppair object
// as the key. It then gets sorted based on the timstamp field
// each value in the map is the parent list it belongs in.
map.put(it.next(), key);
}
}
// Now iterate created map and kill the first 15% plus one to account for zero
Set setPairKeys = map.entrySet();
int itemsToRemove = ((int) (map.size() * 0.15)) + 1;
Iterator iter = setPairKeys.iterator();
while (iter.hasNext() && itemsToRemove > 0) {
Map.Entry entry = (Map.Entry) iter.next();
// kind of backwards on naming. In the map, each key is the objecttimestamppair
// because it has the ordering with the timestamp value. Each value that the
// key references is the key of the list it belongs to.
Object key = entry.getValue();
ObjectTimestampPair pairTimeStamp = (ObjectTimestampPair) entry.getKey();
final CursorableLinkedList list =
((ObjectQueue)(_poolMap.get(key))).queue;
list.remove(pairTimeStamp);
if (toDestroy.containsKey(key)) {
((List)toDestroy.get(key)).add(pairTimeStamp);
} else {
List listForKey = new ArrayList();
listForKey.add(pairTimeStamp);
toDestroy.put(key, listForKey);
}
// if that was the last object for that key, drop that pool
if (list.isEmpty()) {
_poolMap.remove(key);
_poolList.remove(key);
}
_totalIdle--;
_totalInternalProcessing++;
itemsToRemove--;
}
}
destroy(toDestroy, _factory);
}
/**
* Clears the specified pool, removing all pooled instances corresponding to the given key.
*
* @param key the key to clear
*/
public void clear(Object key) {
Map toDestroy = new HashMap();
final ObjectQueue pool;
synchronized (this) {
pool = (ObjectQueue)(_poolMap.remove(key));
if (pool == null) {
return;
} else {
_poolList.remove(key);
}
// Copy objects to new list so pool.queue can be cleared inside
// the sync
List objects = new ArrayList();
objects.addAll(pool.queue);
toDestroy.put(key, objects);
_totalIdle = _totalIdle - pool.queue.size();
_totalInternalProcessing =
_totalInternalProcessing + pool.queue.size();
pool.queue.clear();
}
destroy(toDestroy, _factory);
}
/**
* Assuming Map>, destroy all
* ObjectTimestampPair.value using the supplied factory.
*
* @param m Map containing keyed pools to clear
* @param factory KeyedPoolableObjectFactory used to destroy the objects
*/
private void destroy(Map m, KeyedPoolableObjectFactory factory) {
for (Iterator entries = m.entrySet().iterator(); entries.hasNext();) {
Map.Entry entry = (Entry) entries.next();
Object key = entry.getKey();
Collection c = (Collection) entry.getValue();
for (Iterator it = c.iterator(); it.hasNext();) {
try {
factory.destroyObject(
key,((ObjectTimestampPair)(it.next())).value);
} catch(Exception e) {
// ignore error, keep destroying the rest
} finally {
synchronized(this) {
_totalInternalProcessing--;
allocate();
}
}
}
}
}
/**
* Returns the total number of instances current borrowed from this pool but not yet returned.
*
* @return the total number of instances currently borrowed from this pool
*/
public synchronized int getNumActive() {
return _totalActive;
}
/**
* Returns the total number of instances currently idle in this pool.
*
* @return the total number of instances currently idle in this pool
*/
public synchronized int getNumIdle() {
return _totalIdle;
}
/**
* Returns the number of instances currently borrowed from but not yet returned
* to the pool corresponding to the given key.
*
* @param key the key to query
* @return the number of instances corresponding to the given key currently borrowed in this pool
*/
public synchronized int getNumActive(Object key) {
final ObjectQueue pool = (ObjectQueue)(_poolMap.get(key));
return pool != null ? pool.activeCount : 0;
}
/**
* Returns the number of instances corresponding to the given key currently idle in this pool.
*
* @param key the key to query
* @return the number of instances corresponding to the given key currently idle in this pool
*/
public synchronized int getNumIdle(Object key) {
final ObjectQueue pool = (ObjectQueue)(_poolMap.get(key));
return pool != null ? pool.queue.size() : 0;
}
/**
* Returns an object to a keyed pool.
*
* For the pool to function correctly, the object instance must have been borrowed
* from the pool (under the same key) and not yet returned. Repeated returnObject calls on
* the same object/key pair (with no borrowObject calls in between) will result in multiple
* references to the object in the idle instance pool.
*
* If {@link #getMaxIdle() maxIdle} is set to a positive value and the number of idle instances under the given
* key has reached this value, the returning instance is destroyed.
*
* If {@link #getTestOnReturn() testOnReturn} == true, the returning instance is validated before being returned
* to the idle instance pool under the given key. In this case, if validation fails, the instance is destroyed.
*
* @param key pool key
* @param obj instance to return to the keyed pool
* @throws Exception
*/
public void returnObject(Object key, Object obj) throws Exception {
try {
addObjectToPool(key, obj, true);
} catch (Exception e) {
if (_factory != null) {
try {
_factory.destroyObject(key, obj);
} catch (Exception e2) {
// swallowed
}
// TODO: Correctness here depends on control in addObjectToPool.
// These two methods should be refactored, removing the
// "behavior flag", decrementNumActive, from addObjectToPool.
ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
if (pool != null) {
synchronized(this) {
pool.decrementActiveCount();
allocate();
}
}
}
}
}
/**
* Adds an object to the keyed pool.
*
* Validates the object if testOnReturn == true and passivates it before returning it to the pool.
* if validation or passivation fails, or maxIdle is set and there is no room in the pool, the instance
* is destroyed.
*
* Calls {@link #allocate()} on successful completion
*
* @param key pool key
* @param obj instance to add to the keyed pool
* @param decrementNumActive whether or not to decrement the active count associated with the keyed pool
* @throws Exception
*/
private void addObjectToPool(Object key, Object obj,
boolean decrementNumActive) throws Exception {
// if we need to validate this object, do so
boolean success = true; // whether or not this object passed validation
if (_testOnReturn && !_factory.validateObject(key, obj)) {
success = false;
} else {
_factory.passivateObject(key, obj);
}
boolean shouldDestroy = !success;
ObjectQueue pool;
// Add instance to pool if there is room and it has passed validation
// (if testOnreturn is set)
synchronized (this) {
// grab the pool (list) of objects associated with the given key
pool = (ObjectQueue) (_poolMap.get(key));
// if it doesn't exist, create it
if (null == pool) {
pool = new ObjectQueue();
_poolMap.put(key, pool);
_poolList.add(key);
}
if (isClosed()) {
shouldDestroy = true;
} else {
// if there's no space in the pool, flag the object for destruction
// else if we passivated successfully, return it to the pool
if (_maxIdle >= 0 && (pool.queue.size() >= _maxIdle)) {
shouldDestroy = true;
} else if (success) {
// borrowObject always takes the first element from the queue,
// so for LIFO, push on top, FIFO add to end
if (_lifo) {
pool.queue.addFirst(new ObjectTimestampPair(obj));
} else {
pool.queue.addLast(new ObjectTimestampPair(obj));
}
_totalIdle++;
if (decrementNumActive) {
pool.decrementActiveCount();
}
allocate();
}
}
}
// Destroy the instance if necessary
if (shouldDestroy) {
try {
_factory.destroyObject(key, obj);
} catch(Exception e) {
// ignored?
}
// Decrement active count *after* destroy if applicable
if (decrementNumActive) {
synchronized(this) {
pool.decrementActiveCount();
allocate();
}
}
}
}
/**
* {@inheritDoc}
* Activation of this method decrements the active count associated with the given keyed pool
* and attempts to destroy obj.
*
* @param key pool key
* @param obj instance to invalidate
* @throws Exception if an exception occurs destroying the object
*/
public void invalidateObject(Object key, Object obj) throws Exception {
try {
_factory.destroyObject(key, obj);
} finally {
synchronized (this) {
ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
if (null == pool) {
pool = new ObjectQueue();
_poolMap.put(key, pool);
_poolList.add(key);
}
pool.decrementActiveCount();
allocate(); // _totalActive has changed
}
}
}
/**
* Create an object using the {@link KeyedPoolableObjectFactory#makeObject factory},
* passivate it, and then place it in the idle object pool.
* addObject is useful for "pre-loading" a pool with idle objects.
*
* @param key the key a new instance should be added to
* @throws Exception when {@link KeyedPoolableObjectFactory#makeObject} fails.
* @throws IllegalStateException when no {@link #setFactory factory} has been set or after {@link #close} has been
* called on this pool.
*/
public void addObject(Object key) throws Exception {
assertOpen();
if (_factory == null) {
throw new IllegalStateException("Cannot add objects without a factory.");
}
Object obj = _factory.makeObject(key);
try {
assertOpen();
addObjectToPool(key, obj, false);
} catch (IllegalStateException ex) { // Pool closed
try {
_factory.destroyObject(key, obj);
} catch (Exception ex2) {
// swallow
}
throw ex;
}
}
/**
* Registers a key for pool control.
*
* If populateImmediately is true and
* minIdle > 0, the pool under the given key will be
* populated immediately with minIdle idle instances.
*
* @param key - The key to register for pool control.
* @param populateImmediately - If this is true, the pool
* will be populated immediately.
* @since Pool 1.3
*/
public synchronized void preparePool(Object key, boolean populateImmediately) {
ObjectQueue pool = (ObjectQueue)(_poolMap.get(key));
if (null == pool) {
pool = new ObjectQueue();
_poolMap.put(key,pool);
_poolList.add(key);
}
if (populateImmediately) {
try {
// Create the pooled objects
ensureMinIdle(key);
}
catch (Exception e) {
//Do nothing
}
}
}
/**
* Closes the keyed object pool. Once the pool is closed, {@link #borrowObject(Object)}
* will fail with IllegalStateException, but {@link #returnObject(Object, Object)} and
* {@link #invalidateObject(Object, Object)} will continue to work, with returned objects
* destroyed on return.
*
* Destroys idle instances in the pool by invoking {@link #clear()}.
*
* @throws Exception
*/
public void close() throws Exception {
super.close();
synchronized (this) {
clear();
if (null != _evictionCursor) {
_evictionCursor.close();
_evictionCursor = null;
}
if (null != _evictionKeyCursor) {
_evictionKeyCursor.close();
_evictionKeyCursor = null;
}
startEvictor(-1L);
}
}
/**
* Sets the keyed poolable object factory associated with this pool.
*
* If this method is called when objects are checked out of any of the keyed pools,
* an IllegalStateException is thrown. Calling this method also has the side effect of
* destroying any idle instances in existing keyed pools, using the original factory.
*
* @param factory KeyedPoolableObjectFactory to use when creating keyed object pool instances
* @throws IllegalStateException if there are active (checked out) instances associated with this keyed object pool
* @deprecated to be removed in version 2.0
*/
public void setFactory(KeyedPoolableObjectFactory factory) throws IllegalStateException {
Map toDestroy = new HashMap();
final KeyedPoolableObjectFactory oldFactory = _factory;
synchronized (this) {
assertOpen();
if (0 < getNumActive()) {
throw new IllegalStateException("Objects are already active");
} else {
for (Iterator it = _poolMap.keySet().iterator(); it.hasNext();) {
Object key = it.next();
ObjectQueue pool = (ObjectQueue)_poolMap.get(key);
if (pool != null) {
// Copy objects to new list so pool.queue can be cleared
// inside the sync
List objects = new ArrayList();
objects.addAll(pool.queue);
toDestroy.put(key, objects);
it.remove();
_poolList.remove(key);
_totalIdle = _totalIdle - pool.queue.size();
_totalInternalProcessing =
_totalInternalProcessing + pool.queue.size();
pool.queue.clear();
}
}
_factory = factory;
}
}
destroy(toDestroy, oldFactory);
}
/**
* Perform numTests idle object eviction tests, evicting
* examined objects that meet the criteria for eviction. If
* testWhileIdle is true, examined objects are validated
* when visited (and removed if invalid); otherwise only objects that
* have been idle for more than minEvicableIdletimeMillis
* are removed.
*
* Successive activations of this method examine objects in keyed pools
* in sequence, cycling through the keys and examining objects in
* oldest-to-youngest order within the keyed pools.
*
* @throws Exception when there is a problem evicting idle objects.
*/
public void evict() throws Exception {
Object key = null;
boolean testWhileIdle;
long minEvictableIdleTimeMillis;
synchronized (this) {
// Get local copy of current config. Can't sync when used later as
// it can result in a deadlock. Has the added advantage that config
// is consistent for entire method execution
testWhileIdle = _testWhileIdle;
minEvictableIdleTimeMillis = _minEvictableIdleTimeMillis;
// Initialize key to last key value
if (_evictionKeyCursor != null &&
_evictionKeyCursor._lastReturned != null) {
key = _evictionKeyCursor._lastReturned.value();
}
}
for (int i=0, m=getNumTests(); i 0) &&
(System.currentTimeMillis() - pair.tstamp >
minEvictableIdleTimeMillis)) {
removeObject=true;
}
if (testWhileIdle && removeObject == false) {
boolean active = false;
try {
_factory.activateObject(key,pair.value);
active = true;
} catch(Exception e) {
removeObject=true;
}
if (active) {
if (!_factory.validateObject(key,pair.value)) {
removeObject=true;
} else {
try {
_factory.passivateObject(key,pair.value);
} catch(Exception e) {
removeObject=true;
}
}
}
}
if (removeObject) {
try {
_factory.destroyObject(key, pair.value);
} catch(Exception e) {
// ignored
} finally {
// Do not remove the key from the _poolList or _poolmap,
// even if the list stored in the _poolMap for this key is
// empty when minIdle > 0.
//
// Otherwise if it was the last object for that key,
// drop that pool
if (_minIdle == 0) {
synchronized (this) {
ObjectQueue objectQueue =
(ObjectQueue)_poolMap.get(key);
if (objectQueue != null &&
objectQueue.queue.isEmpty()) {
_poolMap.remove(key);
_poolList.remove(key);
}
}
}
}
}
synchronized (this) {
if (!removeObject) {
_evictionCursor.add(pair);
_totalIdle++;
if (_lifo) {
// Skip over the element we just added back
_evictionCursor.previous();
}
}
_totalInternalProcessing--;
}
}
}
/**
* Resets the eviction key cursor and closes any
* associated eviction object cursor
*/
private void resetEvictionKeyCursor() {
if (_evictionKeyCursor != null) {
_evictionKeyCursor.close();
}
_evictionKeyCursor = _poolList.cursor();
if (null != _evictionCursor) {
_evictionCursor.close();
_evictionCursor = null;
}
}
/**
* Resets the eviction object cursor for the given key
*
* @param key eviction key
*/
private void resetEvictionObjectCursor(Object key) {
if (_evictionCursor != null) {
_evictionCursor.close();
}
if (_poolMap == null) {
return;
}
ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
if (pool != null) {
CursorableLinkedList queue = pool.queue;
_evictionCursor = queue.cursor(_lifo ? queue.size() : 0);
}
}
/**
* Iterates through all the known keys and creates any necessary objects to maintain
* the minimum level of pooled objects.
* @see #getMinIdle
* @see #setMinIdle
* @throws Exception If there was an error whilst creating the pooled objects.
*/
private void ensureMinIdle() throws Exception {
//Check if should sustain the pool
if (_minIdle > 0) {
Object[] keysCopy;
synchronized(this) {
// Get the current set of keys
keysCopy = _poolMap.keySet().toArray();
}
// Loop through all elements in _poolList
// Find out the total number of max active and max idle for that class
// If the number is less than the minIdle, do creation loop to boost numbers
for (int i=0; i < keysCopy.length; i++) {
//Get the next key to process
ensureMinIdle(keysCopy[i]);
}
}
}
/**
* Re-creates any needed objects to maintain the minimum levels of
* pooled objects for the specified key.
*
* This method uses {@link #calculateDeficit} to calculate the number
* of objects to be created. {@link #calculateDeficit} can be overridden to
* provide a different method of calculating the number of objects to be
* created.
* @param key The key to process
* @throws Exception If there was an error whilst creating the pooled objects
*/
private void ensureMinIdle(Object key) throws Exception {
// Calculate current pool objects
ObjectQueue pool;
synchronized(this) {
pool = (ObjectQueue)(_poolMap.get(key));
}
if (pool == null) {
return;
}
// this method isn't synchronized so the
// calculateDeficit is done at the beginning
// as a loop limit and a second time inside the loop
// to stop when another thread already returned the
// needed objects
int objectDeficit = calculateDeficit(pool, false);
for (int i = 0; i < objectDeficit && calculateDeficit(pool, true) > 0; i++) {
try {
addObject(key);
} finally {
synchronized (this) {
pool.decrementInternalProcessingCount();
allocate();
}
}
}
}
//--- non-public methods ----------------------------------------
/**
* Start the eviction thread or service, or when
* delay is non-positive, stop it
* if it is already running.
*
* @param delay milliseconds between evictor runs.
*/
protected synchronized void startEvictor(long delay) {
if (null != _evictor) {
EvictionTimer.cancel(_evictor);
_evictor = null;
}
if (delay > 0) {
_evictor = new Evictor();
EvictionTimer.schedule(_evictor, delay, delay);
}
}
/**
* Returns pool info including {@link #getNumActive()}, {@link #getNumIdle()}
* and currently defined keys.
*
* @return string containing debug information
*/
synchronized String debugInfo() {
StringBuffer buf = new StringBuffer();
buf.append("Active: ").append(getNumActive()).append("\n");
buf.append("Idle: ").append(getNumIdle()).append("\n");
Iterator it = _poolMap.keySet().iterator();
while (it.hasNext()) {
Object key = it.next();
buf.append("\t").append(key).append(" ").append(_poolMap.get(key)).append("\n");
}
return buf.toString();
}
/**
* Returns the number of tests to be performed in an Evictor run,
* based on the current values of _numTestsPerEvictionRun
* and _totalIdle.
*
* @see #setNumTestsPerEvictionRun
* @return the number of tests for the Evictor to run
*/
private synchronized int getNumTests() {
if (_numTestsPerEvictionRun >= 0) {
return Math.min(_numTestsPerEvictionRun, _totalIdle);
} else {
return(int)(Math.ceil(_totalIdle/Math.abs((double)_numTestsPerEvictionRun)));
}
}
/**
* This returns the number of objects to create during the pool
* sustain cycle. This will ensure that the minimum number of idle
* instances is maintained without going past the maxActive value.
*
* @param pool the ObjectPool to calculate the deficit for
* @param incrementInternal - Should the count of objects currently under
* some form of internal processing be
* incremented?
* @return The number of objects to be created
*/
private synchronized int calculateDeficit(ObjectQueue pool,
boolean incrementInternal) {
int objectDefecit = 0;
//Calculate no of objects needed to be created, in order to have
//the number of pooled objects < maxActive();
objectDefecit = getMinIdle() - pool.queue.size();
if (getMaxActive() > 0) {
int growLimit = Math.max(0, getMaxActive() - pool.activeCount - pool.queue.size() - pool.internalProcessingCount);
objectDefecit = Math.min(objectDefecit, growLimit);
}
// Take the maxTotal limit into account
if (getMaxTotal() > 0) {
int growLimit = Math.max(0, getMaxTotal() - getNumActive() - getNumIdle() - _totalInternalProcessing);
objectDefecit = Math.min(objectDefecit, growLimit);
}
if (incrementInternal && objectDefecit > 0) {
pool.incrementInternalProcessingCount();
}
return objectDefecit;
}
//--- inner classes ----------------------------------------------
/**
* A "struct" that keeps additional information about the actual queue of pooled objects.
*/
private class ObjectQueue {
/** Number of instances checked out to clients from this queue */
private int activeCount = 0;
/** Idle instance queue */
private final CursorableLinkedList queue = new CursorableLinkedList();
/** Number of instances in process of being created */
private int internalProcessingCount = 0;
/** Increment the active count for this queue */
void incrementActiveCount() {
synchronized (GenericKeyedObjectPool.this) {
_totalActive++;
}
activeCount++;
}
/** Decrement the active count for this queue */
void decrementActiveCount() {
synchronized (GenericKeyedObjectPool.this) {
_totalActive--;
}
if (activeCount > 0) {
activeCount--;
}
}
/** Record the fact that one more instance is queued for creation */
void incrementInternalProcessingCount() {
synchronized (GenericKeyedObjectPool.this) {
_totalInternalProcessing++;
}
internalProcessingCount++;
}
/** Decrement the number of instances in process of being created */
void decrementInternalProcessingCount() {
synchronized (GenericKeyedObjectPool.this) {
_totalInternalProcessing--;
}
internalProcessingCount--;
}
}
/**
* A simple "struct" encapsulating an object instance and a timestamp.
*
* Implements Comparable, objects are sorted from old to new.
*
* This is also used by {@link GenericObjectPool}.
*/
static class ObjectTimestampPair implements Comparable {
//CHECKSTYLE: stop VisibilityModifier
/**
* Object instance
* @deprecated this field will be made private and final in version 2.0
*/
Object value;
/**
* timestamp
* @deprecated this field will be made private and final in version 2.0
*/
long tstamp;
//CHECKSTYLE: resume VisibilityModifier
/**
* Create a new ObjectTimestampPair using the given object and the current system time.
* @param val object instance
*/
ObjectTimestampPair(Object val) {
this(val, System.currentTimeMillis());
}
/**
* Create a new ObjectTimeStampPair using the given object and timestamp value.
* @param val object instance
* @param time long representation of timestamp
*/
ObjectTimestampPair(Object val, long time) {
value = val;
tstamp = time;
}
/**
* Returns a string representation.
*
* @return String representing this ObjectTimestampPair
*/
public String toString() {
return value + ";" + tstamp;
}
/**
* Compares this to another object by casting the argument to an
* ObjectTimestampPair.
*
* @param obj object to cmpare
* @return result of comparison
*/
public int compareTo(Object obj) {
return compareTo((ObjectTimestampPair) obj);
}
/**
* Compares this to another ObjectTimestampPair, using the timestamp as basis for comparison.
* Implementation is consistent with equals.
*
* @param other object to compare
* @return result of comparison
*/
public int compareTo(ObjectTimestampPair other) {
final long tstampdiff = this.tstamp - other.tstamp;
if (tstampdiff == 0) {
// make sure the natural ordering is consistent with equals
// see java.lang.Comparable Javadocs
return System.identityHashCode(this) - System.identityHashCode(other);
} else {
// handle int overflow
return (int)Math.min(Math.max(tstampdiff, Integer.MIN_VALUE), Integer.MAX_VALUE);
}
}
/**
* @return the value
*/
public Object getValue() {
return value;
}
/**
* @return the tstamp
*/
public long getTstamp() {
return tstamp;
}
}
/**
* The idle object evictor {@link TimerTask}.
* @see GenericKeyedObjectPool#setTimeBetweenEvictionRunsMillis
*/
private class Evictor extends TimerTask {
/**
* Run pool maintenance. Evict objects qualifying for eviction and then
* invoke {@link GenericKeyedObjectPool#ensureMinIdle()}.
*/
public void run() {
//Evict from the pool
try {
evict();
} catch(Exception e) {
// ignored
} catch(OutOfMemoryError oome) {
// Log problem but give evictor thread a chance to continue in
// case error is recoverable
oome.printStackTrace(System.err);
}
//Re-create idle instances.
try {
ensureMinIdle();
} catch (Exception e) {
// ignored
}
}
}
/**
* A simple "struct" encapsulating the
* configuration information for a GenericKeyedObjectPool.
* @see GenericKeyedObjectPool#GenericKeyedObjectPool(KeyedPoolableObjectFactory,GenericKeyedObjectPool.Config)
* @see GenericKeyedObjectPool#setConfig
*/
public static class Config {
//CHECKSTYLE: stop VisibilityModifier
/**
* @see GenericKeyedObjectPool#setMaxIdle
*/
public int maxIdle = GenericKeyedObjectPool.DEFAULT_MAX_IDLE;
/**
* @see GenericKeyedObjectPool#setMaxActive
*/
public int maxActive = GenericKeyedObjectPool.DEFAULT_MAX_ACTIVE;
/**
* @see GenericKeyedObjectPool#setMaxTotal
*/
public int maxTotal = GenericKeyedObjectPool.DEFAULT_MAX_TOTAL;
/**
* @see GenericKeyedObjectPool#setMinIdle
*/
public int minIdle = GenericKeyedObjectPool.DEFAULT_MIN_IDLE;
/**
* @see GenericKeyedObjectPool#setMaxWait
*/
public long maxWait = GenericKeyedObjectPool.DEFAULT_MAX_WAIT;
/**
* @see GenericKeyedObjectPool#setWhenExhaustedAction
*/
public byte whenExhaustedAction = GenericKeyedObjectPool.DEFAULT_WHEN_EXHAUSTED_ACTION;
/**
* @see GenericKeyedObjectPool#setTestOnBorrow
*/
public boolean testOnBorrow = GenericKeyedObjectPool.DEFAULT_TEST_ON_BORROW;
/**
* @see GenericKeyedObjectPool#setTestOnReturn
*/
public boolean testOnReturn = GenericKeyedObjectPool.DEFAULT_TEST_ON_RETURN;
/**
* @see GenericKeyedObjectPool#setTestWhileIdle
*/
public boolean testWhileIdle = GenericKeyedObjectPool.DEFAULT_TEST_WHILE_IDLE;
/**
* @see GenericKeyedObjectPool#setTimeBetweenEvictionRunsMillis
*/
public long timeBetweenEvictionRunsMillis = GenericKeyedObjectPool.DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
/**
* @see GenericKeyedObjectPool#setNumTestsPerEvictionRun
*/
public int numTestsPerEvictionRun = GenericKeyedObjectPool.DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
/**
* @see GenericKeyedObjectPool#setMinEvictableIdleTimeMillis
*/
public long minEvictableIdleTimeMillis = GenericKeyedObjectPool.DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
/**
* @see GenericKeyedObjectPool#setLifo
*/
public boolean lifo = GenericKeyedObjectPool.DEFAULT_LIFO;
//CHECKSTYLE: resume VisibilityModifier
}
/**
* Latch used to control allocation order of objects to threads to ensure
* fairness. That is, for each key, objects are allocated to threads in the order
* that threads request objects.
*
* @since 1.5
*/
private static final class Latch {
/** key of associated pool */
private final Object _key;
/** keyed pool associated with this latch */
private ObjectQueue _pool;
/** holds an ObjectTimestampPair when this latch has been allocated an instance */
private ObjectTimestampPair _pair;
/** indicates that this latch can create an instance */
private boolean _mayCreate = false;
/**
* Create a latch with the given key
* @param key key of the pool associated with this latch
*/
private Latch(Object key) {
_key = key;
}
/**
* Retuns the key of the associated pool
* @return associated pool key
*/
private synchronized Object getkey() {
return _key;
}
/**
* Returns the pool associated with this latch
* @return pool
*/
private synchronized ObjectQueue getPool() {
return _pool;
}
/**
* Sets the pool associated with this latch
* @param pool the pool
*/
private synchronized void setPool(ObjectQueue pool) {
_pool = pool;
}
/**
* Gets the ObjectTimestampPair allocated to this latch.
* Returns null if this latch does not have an instance allocated to it.
* @return the associated ObjectTimestampPair
*/
private synchronized ObjectTimestampPair getPair() {
return _pair;
}
/**
* Allocate an ObjectTimestampPair to this latch.
* @param pair ObjectTimestampPair on this latch
*/
private synchronized void setPair(ObjectTimestampPair pair) {
_pair = pair;
}
/**
* Whether or not this latch can create an instance
* @return true if this latch has an instance creation permit
*/
private synchronized boolean mayCreate() {
return _mayCreate;
}
/**
* Sets the mayCreate property
*
* @param mayCreate true means this latch can create an instance
*/
private synchronized void setMayCreate(boolean mayCreate) {
_mayCreate = mayCreate;
}
/**
* Reset the latch data. Used when an allocation fails and the latch
* needs to be re-added to the queue.
*/
private synchronized void reset() {
_pair = null;
_mayCreate = false;
}
}
//--- protected attributes ---------------------------------------
/**
* The cap on the number of idle instances in the pool.
* @see #setMaxIdle
* @see #getMaxIdle
*/
private int _maxIdle = DEFAULT_MAX_IDLE;
/**
* The minimum no of idle objects to keep in the pool.
* @see #setMinIdle
* @see #getMinIdle
*/
private volatile int _minIdle = DEFAULT_MIN_IDLE;
/**
* The cap on the number of active instances from the pool.
* @see #setMaxActive
* @see #getMaxActive
*/
private int _maxActive = DEFAULT_MAX_ACTIVE;
/**
* The cap on the total number of instances from the pool if non-positive.
* @see #setMaxTotal
* @see #getMaxTotal
*/
private int _maxTotal = DEFAULT_MAX_TOTAL;
/**
* The maximum amount of time (in millis) the
* {@link #borrowObject} method should block before throwing
* an exception when the pool is exhausted and the
* {@link #getWhenExhaustedAction "when exhausted" action} is
* {@link #WHEN_EXHAUSTED_BLOCK}.
*
* When less than or equal to 0, the {@link #borrowObject} method
* may block indefinitely.
*
* @see #setMaxWait
* @see #getMaxWait
* @see #WHEN_EXHAUSTED_BLOCK
* @see #setWhenExhaustedAction
* @see #getWhenExhaustedAction
*/
private long _maxWait = DEFAULT_MAX_WAIT;
/**
* The action to take when the {@link #borrowObject} method
* is invoked when the pool is exhausted (the maximum number
* of "active" objects has been reached).
*
* @see #WHEN_EXHAUSTED_BLOCK
* @see #WHEN_EXHAUSTED_FAIL
* @see #WHEN_EXHAUSTED_GROW
* @see #DEFAULT_WHEN_EXHAUSTED_ACTION
* @see #setWhenExhaustedAction
* @see #getWhenExhaustedAction
*/
private byte _whenExhaustedAction = DEFAULT_WHEN_EXHAUSTED_ACTION;
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* before being returned by the {@link #borrowObject}
* method. If the object fails to validate,
* it will be dropped from the pool, and we will attempt
* to borrow another.
*
* @see #setTestOnBorrow
* @see #getTestOnBorrow
*/
private volatile boolean _testOnBorrow = DEFAULT_TEST_ON_BORROW;
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* before being returned to the pool within the
* {@link #returnObject}.
*
* @see #getTestOnReturn
* @see #setTestOnReturn
*/
private volatile boolean _testOnReturn = DEFAULT_TEST_ON_RETURN;
/**
* When true, objects will be
* {@link org.apache.tomcat.dbcp.pool.PoolableObjectFactory#validateObject validated}
* by the idle object evictor (if any). If an object
* fails to validate, it will be dropped from the pool.
*
* @see #setTestWhileIdle
* @see #getTestWhileIdle
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
private boolean _testWhileIdle = DEFAULT_TEST_WHILE_IDLE;
/**
* The number of milliseconds to sleep between runs of the
* idle object evictor thread.
* When non-positive, no idle object evictor thread will be
* run.
*
* @see #setTimeBetweenEvictionRunsMillis
* @see #getTimeBetweenEvictionRunsMillis
*/
private long _timeBetweenEvictionRunsMillis = DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
/**
* The number of objects to examine during each run of the
* idle object evictor thread (if any).
*
* When a negative value is supplied, ceil({@link #getNumIdle})/abs({@link #getNumTestsPerEvictionRun})
* tests will be run. I.e., when the value is -n, roughly one nth of the
* idle objects will be tested per run.
*
* @see #setNumTestsPerEvictionRun
* @see #getNumTestsPerEvictionRun
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
private int _numTestsPerEvictionRun = DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
/**
* The minimum amount of time an object may sit idle in the pool
* before it is eligible for eviction by the idle object evictor
* (if any).
* When non-positive, no objects will be evicted from the pool
* due to idle time alone.
*
* @see #setMinEvictableIdleTimeMillis
* @see #getMinEvictableIdleTimeMillis
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
private long _minEvictableIdleTimeMillis = DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
/** My hash of pools (ObjectQueue). */
private Map _poolMap = null;
/** The total number of active instances. */
private int _totalActive = 0;
/** The total number of idle instances. */
private int _totalIdle = 0;
/**
* The number of objects subject to some form of internal processing
* (usually creation or destruction) that should be included in the total
* number of objects but are neither active nor idle.
*/
private int _totalInternalProcessing = 0;
/** My {@link KeyedPoolableObjectFactory}. */
private KeyedPoolableObjectFactory _factory = null;
/**
* My idle object eviction {@link TimerTask}, if any.
*/
private Evictor _evictor = null;
/**
* A cursorable list of my pools.
* @see GenericKeyedObjectPool.Evictor#run
*/
private CursorableLinkedList _poolList = null;
/** Eviction cursor (over instances within-key) */
private CursorableLinkedList.Cursor _evictionCursor = null;
/** Eviction cursor (over keys) */
private CursorableLinkedList.Cursor _evictionKeyCursor = null;
/** Whether or not the pools behave as LIFO queues (last in first out) */
private boolean _lifo = DEFAULT_LIFO;
/**
* Used to track the order in which threads call {@link #borrowObject()} so
* that objects can be allocated in the order in which the threads requested
* them.
*/
private LinkedList _allocationQueue = new LinkedList();
}